Cubic boron nitride has hardness next to diamond and excellent thermal conductivity. Such cubic boron nitride is also characterized by low affinity for iron. Cubic boron nitride sintered bodies comprising the cubic boron nitride and a binder phase of metal or ceramics have been applied to cutting tools, wear resistant tools, and the like.
For example, as a known conventional technique related to a tool using such a cubic boron nitride sintered body, Patent Document 1 describes a throw away tip. The throw away tip described in Patent Document 1 includes a tip body of a cemented carbide and a cutting edge tip of a very hard sintered body. The cutting edge tip is joined by brazing to a recess formed in the tip body. In a joint surface of the tip body and the cutting edge tip, gaps are formed partially.
Patent Document 2 describes a cutting insert including an insert body of a cemented carbide and a cutting edge tip of a very hard material, such as a cubic boron nitride sintered body. The cutting edge tip is joined to the insert body by brazing.